Eru Iluvatar lives outside the Universe and time, so can he see everything happening inside Ea all at one time and intervene in specific points in time?
It's not clear how the history of Eä is perceived in the Timeless Halls. It appears as though Ilúvatar can force the experience to be linear (emphasis mine):
Ilúvatar said to [the Ainur]: 'Behold your Music!' And he showed to them a vision, giving to them sight where before was only hearing; arid they saw a new World made visible before them, and it was globed amid the Void, and it was sustained therein, but was not of it. And as they looked and wondered this World began to unfold its history, and it seemed to them that it lived and grew.
The Silmarillion I Ainulindalë
But that's about all we can say conclusively. Since we know that he does intercede (and communicates with certain individuals), we have to conclude that he can interact with the World in a linear way. Whether that's how he actually perceives the World, though, is unknown.